| Rio Grande City to Mattoon (Illinois) | 1,087.57 mi (1,750.27 km) |
| Rio Grande City to Mauldin (South Carolina) | 1,138.89 mi (1,832.87 km) |
| Rio Grande City to Maumee (Ohio) | 1,357.86 mi (2,185.26 km) |
| Rio Grande City to Maumelle (Arkansas) | 698.43 mi (1,124.02 km) |
| Rio Grande City to Mayagüez (Puerto Rico) | 2,096.62 mi (3,374.19 km) |
| Rio Grande City to Mayfield Heights (Ohio) | 1,438.29 mi (2,314.70 km) |
| Rio Grande City to Mays Chapel (Maryland) | 1,563.62 mi (2,516.40 km) |
| Rio Grande City to Maywood (California) | 1,267.64 mi (2,040.07 km) |
| Rio Grande City to Maywood (Illinois) | 1,238.88 mi (1,993.78 km) |
| Rio Grande City to McAlester (Oklahoma) | 617.47 mi (993.72 km) |
| Rio Grande City to McAllen (Texas) | 37.19 mi (59.85 km) |
| Rio Grande City to McCalla (Alabama) | 852.32 mi (1,371.67 km) |
| Rio Grande City to McComb (Mississippi) | 606.67 mi (976.34 km) |
| Rio Grande City to McDonough (Georgia) | 1,003.45 mi (1,614.89 km) |
| Rio Grande City to McFarland (California) | 1,365.07 mi (2,196.88 km) |
